In the state of the art, driver assistance systems are known, e.g. systems to prevent lane departure or emergency steering systems, which provide an automatic steering intervention for assisting a driver.
Furthermore, devices are known in the state of the art, which measure a compressive force applied by the driver to the steering wheel. This can be done capacitively or with optical fibers, which have a lower light transmittance when changing a bend of the fibers. A steering wheel with an optoelectronic sensor is disclosed in the specification of the German patent DE 196 31 502 C1. The steering wheel is equipped with a fiber-optic sensor, which responds to the pressure of the hands of a driver on the steering wheel. The sensor signal varies with the amount of pressure. If e.g. a plurality of pressure sensors is applied to the steering wheel, at least one pressure sensor being arranged in the right region and one pressure sensor being arranged in the left region of the steering wheel, it can be determined whether the driver is holding the steering wheel with one or two hands. In the state of the art it is known to use a plurality of pressure sensors to evaluate, independently from one another, different pressure points on a steering wheel, e.g. the rear side on the left, on the right, or the front side, so as to reach a conclusion about a driver's intention or a driver's attention or the number of hands the driver has on the steering wheel.
Furthermore, it is known in the state of the art to deactivate a driver assistance system that influences the steering of a vehicle, wherein the deactivation is dependent on the driver's applied steering magnitude. German patent laying-open publication DE 10 2004 057 262 A1 discloses a method and a device for deactivating a driver assistance system that influences the steering of a vehicle, dependent on a driver steering magnitude, in particular if this driver steering magnitude exceeds a threshold value. This principle is known for all driver assistance systems as an overruling or overriding of the assistance system by a driver.
The driver assistance system claimed in German patent laying-open publication DE 10 2007 052 258 A1 provides that if the driver places at least one hand on the previously untouched steering wheel, the automatic lateral guidance control of the vehicle switches from the activated state to the deactivated state, and if the hand is removed from the steering wheel then the automatic lateral guidance control is reactivated.
Furthermore, it is known in the state of the art that a mechanical steering system or an electronically amplified steering system (servo steering or power steering) or an electronic steering system (Steer-by-Wire) in a vehicle converts a steering angle at the steering wheel of a vehicle into a cornering or curving path of the vehicle.
Furthermore, driver assistance systems with an automatic steering intervention such as e.g. a driver assistance system for lane keeping (Lane Keeping System) or an emergency steering system or a parking system are known or have already been implemented in today's mass-produced vehicles. The driver can recognize the automatic steering intervention by an automatic deflection of the steering wheel.